he entire world was captivated by NASA's Apollo 11 moon landing 45 years ago this week, but at the time, the mission's success was far from certain. In fact, then President Richard Nixon even had a speech ready should Neil Armstrong and Buzz Aldrin die on the moon.

In preparation for possible catastrophe, presidential speechwriter William Safire prepared a statement for President Nixon. Although the speech remained undelivered, given the success of Apollo 11, its existence underscores some of the concerns regarding the hazards of space travel.

"All involved knew that the risks of an accident on any flight to the moon, especially the first attempt, were high," historian John Logsdon, professor emeritus at George Washington University, told Space.com via email. "Once Armstrong and Aldrin landed, there was particular attention [paid] to the possibility that they might not be able to launch from the moon's surface."